Advise please, damp

[Kat.Tay]

Hi,
1930s 3 bed semi, combi gas boiler, extractor fans in kitchen and downstairs bathroom- next to kitchen, tiny radiator in small kitchen.
I've noticed black mould behind the kitchen unit in the corner of my kitchen, which is making the top of the worktop wet,I can't reach to feel the underneath. I've not noticed before as the microwave is usually situated there. Outside is a big air brick, no water pipes in this area.
Best way to eradicate damp in cupboards, heat or dehumidifier?
Is the massive air brick causing this if so should I fill in?
Many thanks,

 

[Wayners]

Buy a humidity monitor so you can see what's going on.
Lack of air movement in that gap causing the moisture to be dumped on the cold surface.
Need to put some insulation in the gap behind cupboard may help. Will stop the moist air hiting cold wall.
The vent maybe needed to allow the dry air in or for gas appliances?
The microwave will create moisture that could be settling on that cold spot behind cupboard. Maybe move it and see if things improve

 

[Kat.Tay]

Thank you. no gas appliances in kitchen, I've also had a thought, house is 1930s and in every room including the tiny kitchen was a working fireplace, all now removed- blocked chimneys gone too, perhaps this is why the air brick was installed in the kitchen?

 

[Wayners]

There is no easy answer.
If you block vent you trap moisture in the house that will hit the cold surfaces like windows and can cause condensation and surface mould.
If you have vents or open windows to let fresh dry air in this makes rooms cold.

I have 2 giant velux windows which I open for 10mins most evenings around 7pm.
Also open kitchen window for an hour.
Called airing the house.
This don't stop all the condensation on glass in morning but it is way better...

Running a dehumidifier will help.
Watch the humidity sensor.
You can turn off dehumidifier at night if it's 60% or less humidity and you won't have any condensation in morning.

Sounds like you can block up kitchen vent but be aware of consciousness. Just see how it goes..

 

[Koolpc]

Block up kitchen vent. Insulate the wall. Introduce a good extractor fan. Make sure kitchen is not kept really cold all the time.

 

[JohnD]

Is the massive air brick causing this if so should I fill in?

No, the air brick provides ventilation which reduces condensation.

The source of water might perhaps be steam from a kettle or similar appliance, but in a kitchen is very often a plumbing leak.

You don't drape wet washing inside your home, do you?